Spectral efficiency of random CDMA with constant envelope modulation

This paper studies the spectral efficiency of code-division multiple access with constant envelope modulation in the large system limit. Despite the fact that continuous phase modulation is hit by a severe drawback in spectral efficiency as compared to quadrature amplitude modulation on a single user communication link, the gap in terms of spectral efficiency is found to be negligible when employed on a multiple access channel with the CDMA protocol. Accounting for the efficiency of the transmit amplifier, the latter comparison becomes even favorable for constant envelope modulation.